**5. Buried viticulture**

In China, most of the viticulture regions are distributed in cold and midtemperate regions (**Table 2**), these regions are typically affected by the continental monsoon climate with cold, dry winters, and frequent early spring frosts, which can result in severe freezing injury and dehydration risks to branches and roots [32, 33]. It has been acknowledged that, as the main cultivated wine grape variety, the grape and wine quality of *Vitis vinifera* is higher than that of *Vitis labrusca* and various wild species, however, the cold resistance is completely opposite [34]. When the temperature in winter is extremely lower than 15°C, the vines need to be protected to withstand the severe cold, prevent draining, and ensure its safe overwintering. In China, more than 90% of *Vitis vinifera* are distributed in areas where the vines must be buried under a layer of soil during winter (buried viticulture).

In order to choose suitable measures for overwintering, interspecific hybrid breeding, rootstock grafting, wind dispersing cold air, adjusting plant load, soil or material covering, delaying pruning, and other technics were implemented by numerous of researchers all over the world [34, 35]. However, after years of experiments, burying the vines into the soil is still the most effective way to protect vines over winter. In general, the vines are taken down off the trellis after pruning and then buried into the soil (more than 30 cm underground) in the winter, and the soil is removed before the sprouting in the next spring. Both artificial and mechanical methods are used to complete the burying and unearthing of the vines, and this work should be done very carefully to prevent damage to branches and buds. To aid buried viticulture, several cover materials and methods, such as film mulching, industrial cotton, straw mattress, and plastic have been devised and used. Additionally, various types of vine burying and soil removing equipment (or digging machines) have been designed and employed [36].

Because buried management exposes the soil surface in winter and early spring, there is an increased danger of wind erosion and sandstorms, which may cause ecological problems in viticulture regions in northern China. Recently, a new viticultural procedure was reported during winter pruning to ameliorate this phenomenon, by clutching the vine shoots on the wires until next spring. Also, a windbreak was built as a protective function to reduce wind speed, and the dangers of sand storms as well [37].

In conclusion, buried viticulture is labor intensive, costly, and has the potential to cause damage and diseases to branches while also destroying the ecological environment. Buried viticulture further limits mechanized production and all these challenges are serious impediments to China's wine development [34].
